Semiconductor quantum dots (QDs), also known as nano-crystals, are clusters of a finite number of nano scale atoms and molecules, the particle sizes of which are generally within a range of 2-20 nm. At present, the QD materials mainly include IV group, III-V group, and II-VI group QD materials. The QD materials from II-VI group are widely used because they can be easily prepared and their excitation spectra almost cover the whole visible-light range.
When the particle size of a nano-material is reduced to a certain value (typically 10 nm) or less, the energy levels of the electrons in the vicinity of a metal Fermi energy level are changed from quasi-continuous energy level into discrete energy levels, and the energy gaps between the discrete highest occupied molecular orbital energy levels and lowest unoccupied molecular orbital energy levels of the semiconductor nano-particles are widened, causing a blue shift of the absorption spectral peaks and fluorescence spectral peaks; such phenomenon is called quantum-size effect.
The quantum-size effect makes the electro-optical properties of semiconductor QDs greatly changed. The quantum-size effect, arising when the particle size of semiconductor QDs is less than the Bohr radius of exciton, changes the energy level structure of a semiconductor material, converting the energy level structure from a continuous energy band structure into a discrete energy level structure exhibiting molecular properties. With this phenomenon, semiconductor QDs having different particle sizes can be prepared in a same reaction, to produce light emission at different frequencies, thereby facilitating modulation of various luminous colors.
As shown in FIG. 1, a conventional liquid crystal display panel comprises: an array substrate 1 and a color filter substrate 6 which are provided opposite to each other, and a liquid crystal layer 4 provided between the array substrate 1 and the color filter substrate 6. The light emitted from the backlight source of the liquid crystal display panel may be white light, and the white light is a mixture of blue light and yellow light and is impure in color. The white light, after filtered in passing through Red, Green, Blue (R\G\B) trichromatic sections of a color filter layer 22 in the color filter substrate 6, gives rise to monochromatic light, which however contains various colors out of expectations, which results in a screen having a lower color gamut with less bright and less vibrant colors; in addition, when the array substrate 1 and the color filter substrate 6 are oppositely positioned, the device suffers from a larger deviation, and thus it's necessary to make the black matrix 21 wider, which however leads to reduction of aperture ratio.